Chile Pepper News & Info Center

Chile Peppers 101

NMSU’s Chile Pepper Institute breaks down the science of the spicy fruit

By Justin Bannister

From sweet bell peppers, to spicy jalapeños and the super hot Trinidad Scorpion, chile peppers are popular around the world for their various shapes, sizes, colors and heat levels. According to New Mexico State University’s Chile Pepper Institute, that popularity goes back thousands of years.

“It’s interesting that birds do not have the heat receptors, so they can eat the fruits of a very hot chile peppers and spread the seeds.”

“The very first chile peppers evolved around Bolivia in South America,” said Paul Bosland, an NMSU Regents Professor and director of the Chile Pepper Institute. “The early wild peppers were very small and round and spread, probably by birds, for tens of thousands of years to the southern portion of the United States and all the way to the tip of Chile and Argentina.”

Experts believe that when the first humans arrived in the Western Hemisphere, probably around 15,000 years ago, they began to cultivate chile peppers and select them for various traits. The plants also naturally cross-pollinate well, so new varieties are easily developed and constantly being made. Today, there are thousands of chile pepper varieties.

“Early on, chile peppers were used mostly for medicinal purposes,” said Danise Coon, a senior research specialist at the Chile Pepper Institute. “Later, people started integrating them into their food and they started selecting for bigger pods, for different flavors, for colors, and from that is why we have so many different ones today.”

Chile peppers have chemical compounds called capsaicinoids. When humans or other mammals eat or even touch capsaicinoids, it sends a sensation to the brain that the pepper is hot. In addition to food purposes, capsaicin can be used in pain relief patches to relieve muscle aches and pains.

“We believe chile peppers evolved the capsaicinoids to keep mammals from eating them,” Bosland said. “It’s interesting that birds do not have the heat receptors, so they can eat the fruits of a very hot chile peppers and spread the seeds. We, as mammals, have the receptors the capsaicinoids attach to, so we taste chile peppers as being hot.”

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There are thousands of varieties of chile peppers grown across the world.

Today, chile peppers are used in a wide variety of cuisine, depending on the heat level produced. The bell pepper, or the sweet pepper, has no heat at all. Those can be used fresh in salads, or cooked in various dished. Mild to hot chile peppers include poblanos, New Mexico chile pepper varieties and jalapeños. Those can be eaten fresh, dried or cooked and used traditional Mexican dishes and salsas. Further up the heat scale are tabascos and similar peppers used in hot sauces. Habaneros and chiltepins, are considered very hot. Anything above one million Scoville Heat Units, including the Bhut Jolokia and the Trinidad Scorpion are considered super hot.

“There’s a lot of people out there who love that burn,” Coon said. “We can make sauces out of those kinds of peppers, but they really are incredibly hot. The good news, every one of those is edible. As long as it’s a true capsicum, it’s edible. Even if it’s an ornamental chile pepper, it’s edible.”

Chile peppers tend to be rich in vitamins A and C and have other nutritional values as well. The purple pigment present in some peppers is produced by anthocyanin, an antioxidant that can help prevent cell damage in the body. Red chile peppers are rich in carotenoids, which is considered good for eye health.

“A green chile pepper, compared to a red chile pepper isn’t going to be as sweet,” Coon said. “Once you get into the red stage, it’s going to produce more sugar so it’s going to be a little sweeter.”

Going forward, Coon says the Chile Pepper Institute’s efforts will focus on helping chile growers compete in an ever-changing environment, with economic, environmental and sustainability challenges. For years, their research has focused on disease resistance in plants and helping to breed other useful traits in chile peppers to make them better for growers.

“As long as it’s a true capsicum, it’s edible. Even if it’s an ornamental chile pepper, it’s edible.”

NMSU 60 Seconds to Discovery

What makes chile peppers hot?

Paul Bosland, an NMSU Regents Professor and director of the Chile Pepper Institute, explains it is capsaicin that makes chile peppers hot.

Super-Hot Chile Peppers

Researchers at New Mexico State University’s Chile Pepper Institute have discovered that super-hot chile peppers, those with more than one million Scoville Heat Units, are built differently than other peppers. Unlike regular chile peppers, super-hot peppers make the most of the interior space they have available, which can lead to some serious heat.

“What we were interested in finding was why super-hot chile peppers are able to get that hot,” said Paul Bosland, an NMSU Regents Professor and director of the university’s Chile Pepper Institute.

“What we were interested in finding was why super-hot chile peppers are able to get that hot.”

According to Bosland, it has been known that a chile pepper’s heat comes from the chemical compound capsaicin, and that capsaicinoids are found in yellow-colored sacs called vesicles. In most chile peppers, the capsaicinoid vesicles are attached to the fruit’s placenta, where the seeds are located.

With super-hot peppers, those sacs are also found on the fruit wall, and in larger quantities. This gives the pepper far more surface area to pack in capsaicinoid vesicles and to turn up the heat. Peter Cooke, with the NMSU Core University Research Resources Laboratory, was able to make the capsaicinoid sacs fluoresce in both jalapeno peppers and Trinidad Moruga Scorpion peppers and then examined the fruit with university’s electron microscope.

“There, you could see that the jalapeno was only fluorescing on the placenta,” Bosland said, “while the super-hots would fluoresce all over the wall. It’s a very dramatic image to see. Right now, we’re assuming this is a genetic mutation in super-hots because we’ve never seen this in wild chile peppers.”

Bosland said this information can help plant breeders in selecting for new chile pepper varieties that could potentially lead to chile peppers with double the heat of today’s hottest.

“We’ll probably see someone get a three million or four million Scoville Heat Unit fruit down the road,” he said. “This could be particularly helpful for the extraction industry, companies that extract those heat compounds for use in medicine.”